Message-ID: <3B3B47CC.18986911@mailsrv.dii.unisi.it>
Date: Thu, 28 Jun 2001 17:05:48 +0200
From: "Valerio Gabbani" <valerio@dii.unisi.it>
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Lightning
References: <3B3AF18E.19154.AE39A@localhost>
Content-Type: text/plain; charset=iso-8859-2; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

Mike Dennison wrote:

> Not another theoretical piece about lightning damage. This is for real.
>
> Last night we had a bad storm for about an hour - I even saw QRN dots on my
> cable TV.
>
> At 0000 UTC there was a huge bang and the air smelled of burning. The
> mains power went off for a second but came back.
>
> The antenna was undamaged, but my 136kHz pre-amp is not working and,
> more seriously, the mains socket that runs the 'shack' has no power on it. The
> fuses are fine so I suspect the wiring or the double socket!
>
> All domestic applicances are safe, including the computer which was running
> at the time.
>
> The antenna runs into a toroidal transformer so is always earthed and DC
> isolated from the Tx/Rx. I presume that the nearby lightning strike induced
> enough 136kHz RF into the resonant antenna to blow the pre-amp up. This is
> spark transmission at its most powerful.
>
> More info when I have done a post-mortem (autopsy).
>
> Mike, G3XDV (IO91VT)
> http://www.lf.thersgb.net

Dear Mike and All,

i'm very sorry for your bad experience, i think that probably the ligthning  hit
an aerial power line (or one of its pylon)  near you, this explain why the mains
power went off for few seconds, the induced voltage made the rest.

I red with interest all the past discussions on the reflector about Lightning
protection because i have two pole, one about 15 mt high in the middle of a
field, the other 12mt high but on the roof of my house.
So i'm not afraid about possible damage to the radio equipment in case of a
direct strike but about  my and house integrity.
About a couple of mounths ago we have a thunderstorm, the bell tower of a small
church about 1 kilometers away from me was dirctly hit by a lightning, it expoled
and some persons living in a house close to the church ran the risk to die.
Three weeks ago another thunderstorm, i was looking through the windows and
suddenly a cypress about 150 meters from me caught fire hit by a lightning, i
heard a spark noise in my shack an the differential automatic switch of my mains
power switched off but no damage. ( i always disconnect the antenna connectors
and power mains in the shack).
Now i have the pole on the roof earthed with a 35 mm2 section copper cord
connected to the house and radio earth, and  the cables entering in the house
can be disconnected outdoor.
I hope, in case of direct hit, this is sufficient to save at least the house and
the persons inside.

Good luck to all,
Valerio(IK5ZPV)